Oki 8c Plus - Manual (Page 20)

20 OKIPAGE 8c Plus
YCC
This system was developed by Kodak for encoding colour images for
display on video monitors. RGB values are converted to a luminance
component (Y) and chromatic components (C1) and (C2).
CIE
In 1931 the Commission Internationale de l’Eclairage (CIE) devised a
colour system based on the human visual system and is an accepted
standard. This system is not linear and difficult to interpret. There have
been modifications to the system that have given rise to CIELab and
CIELuv.
Colour separations
Each of the process colours are printed separately and must therefore be
specified individually, as the colour is needed. Image data is therefore
split into the primary colours (plus spot colours) before printing.
Colour space
This is a method of describing colour. Some systems are device-dependent
such as RGB and CMYK. The CIE system is a device independent colour
space. Note that all colour models are not colour spaces in their own
right.
Colourants
These are the colours used by a device to reproduce colour. A printing
press uses the CMYK colourants.
Density
In this context, there is no relation to the mass and volume of the object,
but is the ability of the object to absorb light. The more light absorbed,
the higher the object density.
Dithering
A technique where pixels of different colours are placed in close proximity
to give the illusion of another colour as perceived by the human visual
system.
Dot gain
During the printing process, inks may spread causing dots on a page to
print larger than intended. This results in darker tones and colours. The
problem can be compensated for by careful adjustment.
Error diffusion
This is usually associated with halftoning but can also be used with dither.
The error between a pixel and its intended value is propagated to adjacent
pixels to produce a balanced overall effect. Results may sometimes appear
grainy.